From: Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
To: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Cc: LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: EFI mixed mode + perf = rampant triple faults
Date: Thu, 15 Jan 2015 19:41:27 +0000 [thread overview]
Message-ID: <20150115194127.GB12079@codeblueprint.co.uk> (raw)
In-Reply-To: <CALCETrWOxPwoL0zo0UZMk=05uAEqgY-Xovk1=JHwbVtinx3u3w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Wed, 14 Jan, at 10:27:47AM, Andy Lutomirski wrote:
>
> How are you manually triggering an MCE? I've been playing with some
> MCE stuff recently, but the only reasonably reliable way I know of to
> trigger an MCE is using WHEA, and I don't have a box with WHEA, and I
> assume your ASUS T100 doesn't either.
As Borislav mentions, I used 'int $18', solely to trigger the 64-bit
exception handler code paths in the middle of the EFI mixed mode code.
> > Where this won't work so well is at boot time before we jump to the
> > kernel proper. There, we still need to restore the firmware's GDT so
> > that interrupts are serviced correctly before ExitBootServices() (in
> > particular, ia32 Tianocore assumes __KERNEL_CS is a 32-bit CS).
>
> Tianocore makes assumptions about the kernel's GDT layout? Yuck.
No, but 32-bit Tianocore does rely on the second GDT entry being a
32-bit CS.
It has no knowledge of Linux's GDT layout.
--
Matt Fleming, Intel Open Source Technology Center
WARNING: multiple messages have this Message-ID (diff)
From: Matt Fleming <matt@console-pimps.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: LKML <linux-kernel@vger.kernel.org>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: EFI mixed mode + perf = rampant triple faults
Date: Thu, 15 Jan 2015 19:41:27 +0000 [thread overview]
Message-ID: <20150115194127.GB12079@codeblueprint.co.uk> (raw)
In-Reply-To: <CALCETrWOxPwoL0zo0UZMk=05uAEqgY-Xovk1=JHwbVtinx3u3w@mail.gmail.com>
On Wed, 14 Jan, at 10:27:47AM, Andy Lutomirski wrote:
>
> How are you manually triggering an MCE? I've been playing with some
> MCE stuff recently, but the only reasonably reliable way I know of to
> trigger an MCE is using WHEA, and I don't have a box with WHEA, and I
> assume your ASUS T100 doesn't either.
As Borislav mentions, I used 'int $18', solely to trigger the 64-bit
exception handler code paths in the middle of the EFI mixed mode code.
> > Where this won't work so well is at boot time before we jump to the
> > kernel proper. There, we still need to restore the firmware's GDT so
> > that interrupts are serviced correctly before ExitBootServices() (in
> > particular, ia32 Tianocore assumes __KERNEL_CS is a 32-bit CS).
>
> Tianocore makes assumptions about the kernel's GDT layout? Yuck.
No, but 32-bit Tianocore does rely on the second GDT entry being a
32-bit CS.
It has no knowledge of Linux's GDT layout.
--
Matt Fleming, Intel Open Source Technology Center
next prev parent reply other threads:[~2015-01-15 19:41 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-17 16:51 EFI mixed mode + perf = rampant triple faults Andy Lutomirski
2014-12-17 16:54 ` Andy Lutomirski
2014-12-31 18:37 ` Matt Fleming
[not found] ` <20141231183739.GA28946-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
2015-01-14 16:51 ` Matt Fleming
2015-01-14 16:51 ` Matt Fleming
[not found] ` <20150114165151.GA3479-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-01-14 18:27 ` Andy Lutomirski
2015-01-14 18:27 ` Andy Lutomirski
[not found] ` <CALCETrWOxPwoL0zo0UZMk=05uAEqgY-Xovk1=JHwbVtinx3u3w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-14 18:35 ` Borislav Petkov
2015-01-14 18:35 ` Borislav Petkov
2015-01-14 18:38 ` Andy Lutomirski
[not found] ` <CALCETrUEfQY-hnmNV9-PfDbEYLa7bVoRcsZc2X0V+mEAbfNH2g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-14 18:47 ` Borislav Petkov
2015-01-14 18:47 ` Borislav Petkov
2015-01-14 18:49 ` Andy Lutomirski
2015-01-15 19:41 ` Matt Fleming [this message]
2015-01-15 19:41 ` Matt Fleming
[not found] ` <20150115194127.GB12079-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-01-15 19:59 ` H. Peter Anvin
2015-01-15 19:59 ` H. Peter Anvin
[not found] ` <54B81C2E.2090909-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2015-01-15 22:21 ` Matt Fleming
2015-01-15 22:21 ` Matt Fleming
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